Method of preparing epoxidized oils and the like



United States Patent METHOD OF PREPARING EPOXIDIZED OILS AND THE LIKEArvi W. Wahlroos, Minneapolis, Minn., assignor to Archer-Daniels-MidlandCompany, a corporation of Delaware N0 Drawing. Original applicationJanuary 26, 1953, Serial No. 333,372. Divided and this applicationNovemher 4, 1955, Serial No. 545,131

2 Claims. (Cl. 260-6485) In the copending application, Serial No.333,372, filed January 26, 1953, to which I was originally a party andof which the present application is a division, there is disclosed aprocess for the epoxidation of unsaturated higher fatty acid esters andother aliphatic compounds such as acids and amines, by heating suchaliphatic compounds with a catalytic amount of sulfuric acid and withabout /2 mole of acetic acid (e. g. from 0.4 mole to 0.6 mole) for eachmole of unsaturation of the aliphatic compound and about one mole ofhydrogen peroxide (e. g. from about 0.7 mole to 1.1 moles) for each moleof unsaturation of the aliphatic compound.

Preferably the hydrogen peroxide is added directly to the aliphaticcompound and then the acetic and sulfuric acid are added to the reactionmass gradually over an extended period of time. With the concentrationsemployed, this reaction is markedly exothermic and substantial coolingmust take place. However, it has been found that during the addition ofthe acids and the subsequent reaction period the temperature may beallowed to rise up to between 90 F. and 150 F. At the highertemperatures the reaction proceeds more rapidly but again there isdanger of splitting the oxirane ring and decomposing H202 and it ispreferable to use temperatures of between 120 F. and 135 F. Within thisrange the reaction is substantially complete in from 10 to 12 hours.

I have discovered that after the reaction has been completed it is notnecessary to wash the reacted compound. By letting it stand for an houror two (or by centrifuging a gravity separation takes place and theaqueous layer will be found to contain the major proportion of theacetic acid, with substantial percentages of hydrogen peroxide. Thislatter layer can be used further. For example, if the aqueous layercontains approximately 10% of hydrogen peroxide, it may be reacted withfresh oil at the temperature stated until the quantity of hydrogenperoxide is reduced, say, to about 1%. This aqueous layer may then beremoved for recovery of the acetic acid content by rectification. Theoil treated in this way will be only partially epoxidized but may thenbe treated with a fresh charge of hydrogen peroxide and acetic acid(containing sulfuric acid) in an amount sufficient to raise the oxiranelevel to the desired point, say approximately 6%. After the conclusionof this second reaction, the spent aqueous layer from it is againavailable for reaction with fresh oil. By employing this cyclic processvirtually all of the hydrogen peroxide charged into the reaction mixtureis utilized.

After the aqueous layer is separated from the oily layer the H2504 inthe product is neutralized preferably with an excess of alkali (e. g. adilute solution of NaOH) and the mixture is steam-distilled at a reducedpressure at a temperature which may range up to 250 F. to remove aceticacid dissolved in the reaction product. This acetic acid condensate mayalso be rectified and reused so that very little acetic acid is wasted.

My invention may readily be understood from the following illustrativeexample:

650 pounds of soybean oil was used having 1.06 moles of unsaturation per200 grams. There was used 78 pounds or acetic acid again equivalent to0.4 mole of acetic per 1.00 moles of unsaturation. in this run there wasemployed 240 pounds of 46.3% H202 equivalent to one more or 11202 toreach 1.06 moles of unsaturation. 5.2 pounds of sulfuric acid was mixedwith the acetic acid.

This run was made in a four-barrel stainless steel tank equipped withheating or cooling coils and stirrer. The oil was put in this tame and48 pounds of the 46.3% peroxide was added. When a temperature of 125 F.was reached, the remaining 80% of peroxide and the solution of sulfuricacid and glacial acetic acid were added separately and proportionally asfollows: 30% of each during the first hour, 20% of each during thesecond hour, 20% of each during the third hour and the remaining 30% ofeach during the fourth hour.

The batch was held at a temperature between F. and 135 F. for 13 hoursat which time the stirrer was stopped and after 2 /2 hours settling theaqueous layer was drawn oil. The oily layer was treated with dilutesodium hydroxide solution containing 1 /2 equivalents for eachequivalent of sulfuric acid present. The reaction product was thentransferred to a stainless steel autoclave and steam-distilled atreduced pressure up to 250 F. The acetic acid can be recovered andrectified for re-use.

The aqueous layer amounting to 217 pounds contained 28% of acetic acid,1.2% of sulfuric acid and 4.8% of active oxygen as peracetic acid andperoxide. This material was reacted for 12 hours at F. with 642 poundsof fresh soybean oil. The percent of active oxygen in the aqueous layerthen obtained by centrifuging a small sample of the reaction mixture wasreduced to less than 1. At this point agitation was stopped and thereaction mixture was permitted to settle. The aqueous layer can be drawnoff and after decomposing the remaining active oxygen, the acetic acidcan be recovered.

The oily reaction product with an oxirane value of 1.2 was furtherreacted at 130 F. with 225 pounds of 50% H202, 87.8 pounds of aceticacid (80%) and 4 pounds of sulfuric acid. These reactants were addedproportionally in the manner already described. After a total of 10hours the oxirane content had reached 6%. The stirrer was then stoppedand the batch was allowed to settle. The aqueous layer was withdrawn forre-use as described and the oily layer after neutralization was giventhe same type of steam distillation as was used in the other batches.

It will be seen from the foregoing that it is possible to obtain a highpercentage of oxidized oil which may run up close to 80% and at the sametime to operate the process extremely efiiciently, as there is verylittle loss of reagents.

It is understood that the example given is only by way of illustrationand is not intended to constitute a limitation upon the scope of myinvention.

What I claim is:

1. In the process for the epoxidation of organic compounds containing along-chain unsaturated aliphatic group selected from the groupconsisting of acids, esters and amides by heating such compound in thepresence of a catalytic amount of sulfuric acid together with aboutone-half a mole of acetic acid for each mole of unsaturation of saidcompound and about one mole of hydrogen peroxide for each mole ofunsaturation of such compound, the steps of removing water and watersoluble bodies from the reacted product by gravity separation and usingsuch aqueous layer for treating additional quantities of the unsaturatedorganic compound without restoring the peroxide content to its originalproportion relative to the acetic acid.

3 4 2. A process as specified in claim 1 which comprises ReferencesCited in the file of this patent the additional steps of separating thewater and water UNITED STATES PATENTS soluble bodies from the reactedproduct by gravity separation and further reacting the oily materialwith addi- 2,485,160 Nlederhauser 1949 tional quantities of acetic acidcontaining catalytic 5 2,567,930 Fmdlfiy P 1951 amounts of sulfuric acidand hydrogen peroxide to bring OTHER REFERENCES the reaction product upto the desired oxirane value. Findley I A C S 412 414 (1945)

1. IN THE PROCESS FOR THE EPOXIDATION OF ORGANIC COMPOUNDS CONTAINING ALONG-CHAIN UNSATURATED ALIPHATIC GROUP SELECTED FROM THE GROUPCONSISTING OF ACIDS, ESTERS AND AMIDES BY HEATING SUCH COMPOUND IN THEPRESENCE OF A CATALYTIC AMOUNT OF SULFURIC ACID TOGETHER WITH ABOUTTONE-HALF A MOLE OF ACETIC ACID FOR EACH MOLE OF UNSATURATION OF SAIDCOMPOUND AND ABOUT ONE MOLE OF HYDROGEN PEROXIDE FOR EACH MOLE OFUNSATURATION OF SUCH COMPOUND, THE STEPS OF REMOVING WATER AND WATERSOLUBLE BODIES FROM THE REACTED PRODUCT BY GRAVITY SEPARATION AND USINGSUCH AQUEOUS LAYER FOR TREATING ADDITIONAL QUANTITIES OF THE UNSATURATEDORGANIC COMPOUND WITHOUT RESTORING THE PEROXIDE CONTENT TO ITS ORIGINALPROPORTION RELATIVE TO THE ACETIC ACID.